diff --git a/planet/models/species.py b/planet/models/species.py
index 739879b..c5399e6 100644
--- a/planet/models/species.py
+++ b/planet/models/species.py
@@ -17,9 +17,9 @@ class Species(db.Model):
     description = db.Column(db.Text)
 
     sequences = db.relationship('Sequence', backref='species', lazy='dynamic', cascade='all, delete-orphan')
-    networks = db.relationship('ExpressionNetworkMethod', backref='species', lazy='dynamic')
-    profiles = db.relationship('ExpressionProfile', backref='species', lazy='dynamic')
-    expression_specificities = db.relationship('ExpressionSpecificityMethod', backref='species', lazy='dynamic')
+    networks = db.relationship('ExpressionNetworkMethod', backref='species', lazy='dynamic', cascade='all, delete-orphan')
+    profiles = db.relationship('ExpressionProfile', backref='species', lazy='dynamic', cascade='all, delete-orphan')
+    expression_specificities = db.relationship('ExpressionSpecificityMethod', backref='species', lazy='dynamic', cascade='all, delete-orphan')
 
     def __init__(self, code, name, data_type='genome',
                  color="#C7C7C7", highlight="#DEDEDE", description=None):
diff --git a/planet/templates/expression_cluster.html b/planet/templates/expression_cluster.html
index 48313cd..00250f0 100644
--- a/planet/templates/expression_cluster.html
+++ b/planet/templates/expression_cluster.html
@@ -86,10 +86,10 @@ <h1>Cluster: {{ cluster.name }}<br /><small>{{ cluster.method.method }}</small><
                             <table class="table  table-striped" id="SimilarClusters">
                                 <thead>
                                     <tr>
-                                        <th data-sort="string-ins">Cluster</th>
+                                        <th data-sort="string-ins">Clustering Method</th>
                                         <th data-sort="string-ins">Target</th>
                                         <th data-sort="float">Jaccard index</th>
-                                        <th data-sort="string-ins">Gene Family Method</th>
+                                        <th data-sort="string-ins">Gene Family Method <span class="text-muted">(for comparison)</span></th>
                                         <th>Actions</th>
                                     </tr>
                                 </thead>